Inspection device, toolstring, and method

Abstract

An inspection device (1) for inspecting an inside of a tubular structure (92) downhole, the inspection device (1) comprises a main body (2), a plurality of image sensors (4), and at least one lighting means (5) accompanying each image sensor (4), the main body (2) having an outer surface (22), an upper portion (24) adapted to connect to surface equipment, and a lower portion (28), and forms a longitudinal axis (96), wherein: - the lighting means (5) are arranged to emit light radially outwardly from the inspection device (1); - the image sensors (4) are arranged in a plane (32) and facing radially outwardly from the inspection device (1); and - the inspection device (1) comprises at least one lens (42, 52) for each image sensor (4) and its accompanying lighting means (5) which is / are separate from the other image sensor(s) (4) and their accompanying lighting means (5)

Description

[0001] INSPECTION DEVICE, TOOLSTRING, AND METHOD

[0002] The disclosure relates to an inspection device for inspecting an inside of a tubular structure downhole. The inspection device comprises a main body, a plurality of image sensor, and at least one lighting means accompanying each image sensor. A toolstring comprising the inspection device and a method for using the toolstring are also disclosed.

[0003] Designing downhole tools presents numerous challenges. These tools must possess sufficient strength both along and around a longitudinal axis to withstand axial forces, torsional forces, and bending forces. Other challenges are space constraints, as these tools must be able to enter a variety of wellbores and the fact taht that each wellbore may have unique characteristics; for instance, some may be filled with liquid, others with gas, or a combination of both. Yet another challenge is to create high-quality inspection outputs, such as photographs or videos, with minimal distortion. Downhole cameras present additional challenges as the use of continuous metal housings is not possible. Glass sections are required to be placed within the structure of the tool to allow light to exit and enter. These glass sections reduce the structural integrity of the tool.

[0004] WO2022133533 discloses an image capturing assembly comprising an elongated body fitted with multiple cameras and lighting means positioned along a longitudinal axis. While this arrangement may enhance structural strength along the longitudinal axis, providing a 360-degree view of an inside of a tubular structure may be challenging.

[0005] US11215917 discloses an inspection assembly viewpoint. The inspection assembly includes multiple cameras arranged along a transverse plane to provide a 360-degree image. Multiple light emitters are positioned in a first plane and a second plane, perpendicu-

[0006] P31279PC00 Description and claims for PCT lar to a longitudinal axis. The light emitters in both the first and second planes are shielded by a window element. However, as these window elements are annular, their inclusion significantly reduces the structural strength of the inspection assembly.

[0007] An inspection device may be deployed in a series of consecutive operations in various production wells. These operations may involve varying restrictions regarding tubular structure size, different types of forces the inspection device must withstand, and different well conditions, such as whether the wells are filled with liquid or gas, which may impact the quality of inspection outputs. To ensure the versatility of the inspection device, it is desirable to minimize adaptations between subsequent operations.

[0008] Downhole environments may be harsh, causing exterior damage to the tools, such as scratches and deformations. These environments are often very warm, necessitating the design of tools that may effectively dissipate heat.

[0009] The disclosure has for its object to remedy or to reduce at least one of the drawbacks of the prior art, or at least provide a useful alternative to prior art. The object is achieved through features, which are specified in the description below and in the claims that follow.

[0010] The disclosure is defined by the independent patent claims. The dependent claims define advantageous embodiments of the disclosure.

[0011] In a first aspect the disclosure relates more particularly to an inspection device according to claim 1.

[0012] In an embodiment, the main body may be designed such that its longitudinal axis is centrally positioned.

[0013] The inspection device may be desirable for operations that require the inspection of the interior of a tubular structure, such as a pipe, a casing, a liner, a sleeve, or any areas suspected of deformation or damage inside a well. It may also be used to inspect the interior of a blow-out preventer (BOP), a wellhead, a lubricator, or any other tubular structures associated with a hydrocarbon-producing well.

[0014] P31279 description and claims for PCT The upper portion of the inspection device may be connected to surface equipment via an elongated member. The elongated member may be a slick line, a wireline, a coiled tubing, drill pipe or any other suitable member known within the art for connecting a downhole tool to the surface.

[0015] The lower portion of the inspection device may comprise a lower connection designed to connect to a purpose tool. The purpose tool may be a shifting tool for a sleeve, a cleaning tool in the form of a rotating brush, a rotating milling tool, or any other purpose tool suitable for downhole operations.

[0016] In one embodiment, the inspection device may be positioned between two purpose tools in a toolstring, such as between a stroker and a shifting tool for shifting a sleeve. In this configuration, the inspection device may be subjected to large axial forces and potentially bending forces. In another embodiment of the toolstring, the inspection device may be positioned between a rotational drive, such as a milling unit, and a rotational anchor section, such as a tractor. In this case, the inspection device may be subjected to large rotational forces.

[0017] If an operation only involves inspection and no other operations, the lower connection may be plugged with a blind plug. In an embodiment of the inspection device, there may not be a lower connection. The main body of the inspection device has an outer surface with an outer diameter, which may be used to determine if the inspection device meets size restrictions within the tubular structures forming a wellbore.

[0018] The lighting means may include LED light emitters, light bulbs, or any other means known in the art to illuminate the inside of the tubular structure.

[0019] In an embodiment, the inspection device may comprise between 2 and 6 image sensors, more preferably between 3 and 6 sensors, and preferably 4 image sensors. The image sensors are positioned in the plane and are adapted to capture a 360-degree image of the inside of the tubular structure. The image sensors may capture an image or a motion picture comprising a plurality of subsequent images.

[0020] In an embodiment, the image sensors may be positioned to point in a direction perpen-

[0021] P31279 description and claims for PCT dicular to the longitudinal axis. This may be advantageous when inspecting an area for damages or deformations, as it results in less distortion in the images. In another embodiment, the image sensors may be positioned to point in a direction that creates an angle of less than ninety degrees relative to the longitudinal axis. This may be desirable when it is necessary to inspect an ongoing operation performed by the purpose tool, such as shifting a sleeve.

[0022] Scratches and deformations to the external surface of toolstrings are expected in downhole operations. As such, the inspection device comprises at least one lens for each image sensor and its accompanying lighting means, which are separate from the other image sensors and their accompanying lighting means. This design allows for a more cost- effective repair if a lens needs to be replaced. Having separate lenses for each image sensor and the accompanying lighting means also allows the lenses to be replaced with minimal effort, as the individual lenses may be easily accessible and replaceable from the outside with minimal disassembly of adjacently positioned parts.

[0023] The plane in which the image sensors are arranged may be transverse to the longitudinal axis. This provides minimum of processing to create a sector view of the inside of the tubular structure. Further, the arrangement of image sensors in a plane transverse to the longitudinal axis allows for the positioning of the lighting means along a common lighting plane. This configuration, where the lighting means point radially outward, facilitates cross lighting, a technique where two light beams intersect, enhancing the illumination of the interior of the tubular structure. The common lighting plane may be perpendicular to the longitudinal axis, with the lighting means pointing radially outward.

[0024] The image sensors are in a circumferential array. This simplifies the process of creating a single 360-degree sector image from the images captured by each image sensor. This arrangement also eliminates the need to move the inspection device to capture a 360- degree sector image of the interior of the tubular structure. The 360-degree sector image may be defined as an image that is observed radially from a tubular structure longitudinal axis and spanning a full circle of 360 degrees around this axis. In an embodiment, the image lenses may be spaced equidistantly around the main body's circumference.

[0025] P31279 description and claims for PCT The lighting means, which may in an embodiment encircle the image sensor, is designed to emit light radially outward from the inspection device. The light may be emitted perpendicularly relative to the longitudinal axis or radially from the main body in a direction forming an angle with the longitudinal axis.

[0026] The lighting means may be spaced apart from the image sensor along the longitudinal axis. This arrangement allows for the heat generated by these components to be distributed over a larger area, compared to if they were collocated, such as when the lighting means encircle the image sensor. Additionally, this configuration may enhance the structural strength of the inspection device, as compared to having the lighting means and the image sensor in common a plane perpendicular to the longitudinal axis. By spacing the image sensor and the lighting means apart along the longitudinal axis, the load-bearing portions of the main body extending between the upper and lower portions on each side of the image sensor contributes to the structural strength of the inspection device. This arrangement also improves heat dissipation by spacing out the heat-generating devices. Holes for images sensors and lighting means weaken the structural integrity of the inspection device, and thereby its strength. The inspection device has therefore been designed to maximize the cross-sectional area of the load-bearing portions around the image sensors and lighting means without increasing the outer diameter beyond that of the rest of the body of the downhole tool. The holes in the inspection device have been made as small as possible while maintaining a sufficient view angle from each of the image sensors and sufficient lighting from each of the lighting means. Design of the lenses, as will be discussed below, has been optimised to enable such reduction in holes sizes. Pack- ers / seals and clearances have been included to ensure sufficient sealing of the inspection device both under compression and tension.

[0027] In one embodiment, the body of the inspection device, including in the area between the image sensors and lighting means, may be made from stainless steel, preferably from grade 17-4 PH, which is very hard and with high ultimate tensile strength. Lenses covering the openings over the image sensors and lighting means are preferably made from sapphire glass. The thickness and shape of the sapphire glass lenses will typically be made to withstand a pressure of at least 10.000 psi (690 bar). The strongest axis of the crystal,

[0028] P31279 description and claims for PCT usually referred to as the "c-axis", may preferably be arranged perpendicularly to the length axis of the inspection device, i.e. in the direction of the pressure gradient.

[0029] Each image sensor may be accompanied by at least two lighting means spaced apart along the longitudinal axis from the image sensor, at least one lighting means being positioned on each side of the image sensor. This configuration allows the inspection device to illuminate the area in front of the image sensor more efficiently, as light may be distributed uniformly from two sides of the image sensor. The cross lighting from the lighting means of the adjacently positioned image sensor, combined with the lighting means provided on each side of the image sensor, may provide a more efficient illumination of the area in front of the image sensor. Moreover, the structural strength along the longitudinal axis may not be compromised to any significant degree, as the portions of the main body on each lateral side of the image sensor remain unaffected since the at least two lighting means and the image sensor are spaced along the longitudinal axis, whereby portions of the body form a frame structure around the sensors and light sources to compensate for loss of strength.

[0030] Downhole tools are prone to wear on the outer surface of the main body. Each image sensor, its accompanying lighting means, and the least one lens may be positioned in a recess in the main body. To protect the lens, image sensor, and lighting means from damage, they may be positioned in a recess in the main body. Each recess may comprise a chamfer on each side of the image sensor along the longitudinal axis, preventing any perpendicular edges from catching inside any profiles within the tubular structure and reducing the likelihood of debris build-up in front of the image sensor and the lighting means.

[0031] In an embodiment, the inspection device may comprise one recess for each image sensor and one recess for each accompanying lighting means. Alternatively, the inspection device may comprise one recess for each image sensor and the accompanying lighting means. Each recess may not abut an adjacently positioned recess, therefore creating the portions or regions that may have a full outer diameter between the upper and lower portions on each side of the image sensors. This provides additional support to prevent lens scratching due to sudden geometry changes inside the tubular structure, such as in-

[0032] P31279 description and claims for PCT side a sidepocket mandrel.

[0033] In an alternative embodiment, the inspection device may comprise one elongated lens for each image sensor and its respective lighting means. This design allows for easy lens replacement with minimal effort. However, a single elongated lens for both the image sensor and the lighting means may result in any imperfections, such as scratches, lighting up and degrading the quality of the image sensor output. This issue may be resolved by separating the elongated lens into sectors so that light from the lighting means does not enter the part of the lens in front of the image sensor.

[0034] To simplify the lens design and reduce costs, the inspection device may comprise a plurality of lenses. This means the inspection device may comprise a plurality of image lenses and a plurality of lighting lenses. Each image sensor may have an image lens, and each lighting means may have a lighting lens. This allows for the use of less complex lenses and means that if a lens gets scratched, only that single lens needs to be replaced, not a lens that covers both the image sensor and the lighting means. It also adds versatility, as the inspection device may be adapted for different operations if needed. The lighting lens may be adjusted and optimised independently of the image lens.

[0035] The inspection device may be designed so that each lens may be easily replaced. In an embodiment, the inspection device may comprise a cover for each image sensor and its accompanying lighting means. The cover may be removed radially relative to the longitudinal axis, meaning that only a minimum number of adjacent parts need to be disassembled to replace the lens, the image sensor, the image lens, the lighting means, the lighting lens, or a combination of these. This design makes it easy to adapt the inspection device for different downhole conditions and to replace any components that malfunction.

[0036] The image lens may be a camera lens. In an embodiment, the image lens may be a fisheye lens, which may capture a 180-degree field of view and cover a large area in front of the image sensor. This may be desirable in some scenarios. However, a fisheye lens distorts dimensions, which may not be desirable for some operations, such as evaluating the size of a damaged area.

[0037] P31279 description and claims for PCT In an embodiment, the image lens may be a plano-concave lens comprising a flat side and a concave side, the concave side of the image lens facing the image sensor. This allows for a wide field of view with minimal image distortion, requiring less processing compared to other lenses, such as the fisheye lens.

[0038] The lighting lens may be a diffuser lens, a spreading lens, or any other suitable lens. In an embodiment, the lighting lens may be a plano-concave lens comprising a flat side and a concave side, the concave side of the lighting lens facing away from the lighting means. This allows the lens to spread light over a larger area in front of the image sensor than a flat lens, which may create a spotlight effect that makes inspection difficult.

[0039] As mentioned earlier, the main body of the inspection device may comprise portions that extend on each side and along the longitudinal axis of each image sensor and its associated lighting source. The main body may comprise one portion between each image sensor, each portion extending along the longitudinal axis between the upper portion and the lower portion and having a full outer diameter, i.e. the same diameter as the inspection device outside the area of the image sensors and lighting means. For a specific arc angle, the area in a cross-sectional plane normal to the length axis increases along the radius of the outer surface. This is advantageous for transferring axial forces through the inspection device. Furthermore, to transfer or absorb torsional or bending forces, it is beneficial to have material along or as close as possible to the outer diameter of the inspection device. Having portions with the full outer diameter reduces design complexity, as it is easier to achieve high structural strength compared to if material is closer to the center of the inspection device.

[0040] Additionally, the load-bearing portions of the inspection device extending between the upper and the lower portion thereof may allow the center along the longitudinal axis of the inspection device to be open so that at least one feedthrough wire may be guided through it, connecting the upper portion to the lower portion with minimal complexity. The inspection device may include at least one feedthrough wire connecting the top connection with the bottom connection. The inspection device may comprise an opening for at least one feedthrough wire between the upper portion and the lower portion. The

[0041] P31279 description and claims for PCT feedthrough wire(s) may be adapted for at least one of power and communication between the upper connection and the lower connection. This allows the inspection device to be placed above, below, or between the purpose tools in a toolstring without imposing limitations on the purpose tools regarding power and communication.

[0042] In an embodiment, the inspection device may be filled with gas. The tubular structure in which the inspection device is used may be filled with a gas or a liquid. The process of inspecting the tubular structure filled with gas might be less challenging than inspecting one filled with liquid. This is because a tubular structure filled with liquid, which may be a combination of mud and water or other liquids, may have reduced visibility, thereby making the inspection process more demanding. Furthermore, capturing an image or video in a liquid filled environment with a gas-filled inspection device may be challenging due to the difference in refractive indices between gas and liquid. When light passes from liquid (having a higher refractive index) to gas (with a lower refractive index), it bends away from a normal line. This phenomenon, known as refraction, may distort the image captured by the image sensor. The distortion is more pronounced when the lighting or image lens has gas on one side and the liquid on the other, as the light undergoes refraction at the gas-liquid interface. This may lead to distorted or unclear images, making imaging in a liquid filled environment a challenge with a gas-filled inspection device. The lens, or the image lens and the lighting lens, may be designed to function optimally in a liquid-filled environment. The image lens, such as the plano-concave lens, may be designed to be optimised or substantially optimised for a liquid-filled environment surrounding the inspection device, which may somewhat reduce functionality in a gas-filled environment. This is because the requirements for the image lens are higher / more demanding in a liquid- filled environment than in a gas-filled environment and since captured images from a gas- filled environment may be satisfactory even if generated from a non-optimal optic configuration. Alternatively, or additionally, the lighting lens may be designed to be optimised or substantially optimised for a liquid-filled environment, as the liquid-filled environment has higher / more demanding requirements for the lighting lens than a gas-filled environment.

[0043] The inspection device, the lens, or the image lens and the lighting lens may be set up to

[0044] P31279 description and claims for PCT operate optimally in the liquid-filled environment. This allows the inspection device to be used in both gas and liquid-filled environments, increasing versatility and avoiding the need for time-consuming adaptation between different environments.

[0045] In a second aspect the disclosure relates more particularly to a toolstring for inspecting an inside of a tubular structure downhole, wherein:

[0046] - the toolstring comprises an inspection device according to the first aspect of the disclosure; and

[0047] - the upper portion is connected to a surface equipment.

[0048] The lower portion may be connected to a purpose tool.

[0049] The inspection device may be designed to inspect a specific area within the tubular structure. The inspection device may be positioned to control an area that the purpose tool is preparing to work on, is currently working on, or has already worked on. In an embodiment, the inspection device may be arranged within the toolstring to monitor the operation of the purpose tool in real time.

[0050] As mentioned in relation to the first aspect of the disclosure, in an embodiment of the toolstring, the inspection device may be positioned between two purpose tools, such as between a stroker and a shifting tool for shifting a sleeve. In another embodiment of the toolstring, the inspection device may be positioned between a rotational drive, such as a milling unit, and a rotational anchor section, such as a tractor. In yet another embodiment of the toolstring, the inspection device may be positioned below the purpose tool, such as below the shifting tool.

[0051] The inspection device may be positioned in the toolstring such that it may inspect at least one of a pre-purpose-tool operation, during a purpose-tool operation, and a post- purpose-tool operation.

[0052] When operations deviate from the plan, such as when a sleeve fails to shift, determining the cause may be challenging. The issue may be debris, wear in the tubular structure, or malfunctioning equipment. Identifying a probable cause through testing is not only timeconsuming but also difficult to execute accurately due to the challenge of replicating

[0053] P31279 description and claims for PCT downhole conditions. Therefore, employing the inspection device to examine the tubular structure before, during, and / or after a specific task may help identify reasons for operational deviations. By having the inspection device and purpose tools as a part of the same tool string, addition runs into the well (or other tubular structure) may be avoided. This approach may eliminate the need for time-consuming and potentially inaccurate testing.

[0054] In a third aspect the disclosure relates more particularly to a method for inspecting an inside of a tubular structure, wherein the method comprises the steps of:

[0055] - providing a toolstring according to the second aspect of the disclosure;

[0056] - displacing the toolstring to a desired position inside the tubular structure; and

[0057] - inspecting the inside of the tubular structure.

[0058] The tubular structure may be located downhole. However, the tubular structure alternatively be a blow-out-preventer (BOP), a wellhead, a lubricator etc., located outside the wellbore.

[0059] The toolstring may comprise a purpose tool and the method may comprise the step of performing an operation within the tubular structure using the purpose tool.

[0060] The method may comprise the step of inspecting the tubular structure while the operation is performed.

[0061] The method may comprise the step of inspecting the tubular structure after the operation is completed.

[0062] To prevent repetition in the description of features, technical effects, and disclosed embodiments, any information disclosed in relation to the first, second, or third aspect may be equally applicable to all three aspects of the disclosure. This approach ensures a comprehensive understanding of the disclosure without unnecessary repetition.

[0063] In the following is described an example of a preferred embodiment illustrated in the accompanying drawings, wherein:

[0064] Fig. 1 shows, in a sideview, an inspection device positioned within a tubular structure;

[0065] P31279 description and claims for PCT Fig. 2 shows the inspection device in a different scale and a partially exploded view;

[0066] Fig. 3a shows a cross-sectional view A-A as indicated in Fig 1;

[0067] Fig. 3b shows a cross-sectional view B-B as indicated in Fig 1;

[0068] Fig. 3c shows a cross-sectional view C-C as indicated in Fig 1;

[0069] Fig. 4a shows a toolstring that comprises the inspection device;

[0070] Fig. 4b shows an alternative toolstring that comprises the inspection device; and

[0071] Fig. 5 shows a method for inspecting an inside of the tubular structure.

[0072] Any positional indications refer to the position shown in the figures. In the figures, same or corresponding elements are indicated by same reference numerals. For clarity reasons, some elements may in some of the figures be without reference numerals. A person skilled in the art will understand that the figures are just principal drawings. The relative proportions of individual elements may also be distorted.

[0073] Fig. 1 shows an inspection device, labeled as 1, situated within a tubular structure 92. The inspection device 1 comprises a main body 2 with an outer surface 22. The main body 2 has an upper portion 24 with an upper connection 26 and a lower portion 28 with a lower connection 29. The upper connection 26 is connected to an electronics section 97, which in turn connects to surface equipment (not shown) via a wireline 99. The lower connection 29 is connected to a crossover designed to connect to a lower purpose tool 140, best seen in Fig. 4a.

[0074] Referring now to Figs. 1, 2, 3a, and 3b, the main body 2 has a central longitudinal axis 96. The inspection device 1 comprises four image sensors 4, positioned equidistantly around the circumference of the main body 2 in a circumferential array 34. Each image sensor 4 is located in a plane 32 perpendicular to the longitudinal axis 96, with each image sensor 4 facing radially outward from the longitudinal axis 96. In the shown embodiment, the image sensor 4 is a camera designed to capture images.

[0075] P31279 description and claims for PCT Each image sensor 4 is accompanied by lighting means 5 on both sides along the longitudinal axis. The lighting means 5, here in the form of LED light emitters, are spaced apart from the image sensor 4 along the longitudinal axis 96, forming a load-bearing portion 36 between adjacent image sensors 4. Each portion 36 extends between the upper portion 24 and the lower portion 28 of the inspection device l and has a full diameter equal to that of the outer surface 22 of the main body 2 and forms a load-bearing frame around the image and light sensors 4 ,5. This can also be seen by comparing Fig. 3a, which as a cross-section through the plane of the image sensors 4 and Fig. 3b which is a crosssection through the lower plane of lighting means 5. The primary function of the loadbearing portions 36 is to provide structural strength to the inspection device 1 by adding material / metalwork in regions that offer maximum strength compared to their cross- sectional footprint. The structural integrity of the main body 2 of the inspection device 1, enables the use of various purpose tool below the inspection device, also including mechanical tool, such as mechanical cleaning tools, with force transfer across the inspection device 1. Tests and finite element simulations performed with an inspection tool according to the present invention and as shown in Figs. 2-3, have shown that it is able to withstand tensile loads of at least 15 tons and pressures exceeding 10.000 psi (690 bar) both in the length direction and normal to the length axis.

[0076] Each image sensor 4 is shielded by an image lens 42. The image lens 42 has a concave side 44 facing the image sensor 4 and a flat side 46 facing away from the image sensor 4, i.e., radially away from the image sensor 4 and the longitudinal axis 96. This configuration allows the image sensor 4 to capture an image of a large area in front of it, enabling the four image sensors 4 combined to capture an image covering 360 degrees of an internal wall of the tubular structure 92. There may or may not be a degree of overlap between the areas captured by the various image sensors.

[0077] Each lighting means 5 includes a lighting lens 52. The lighting lens 52 has a concave side 54 and a flat side 56, with the flat side 56 facing towards the lighting means 5 and the concave side 54 facing radially away from the lighting means 5 and the longitudinal axis 96. This design allows light emitted from the lighting means 5 to spread across an area in front of the nearby image sensor 4. Each lighting means 5 is designed to allow a cross-

[0078] P31279 description and claims for PCT lighting effect with adjacently positioned lighting means 5, illuminating 360 degrees of the internal wall of the tubular structure 92.

[0079] Referring now to Figs. 2 and 3c, each image sensor 4 and its accompanying lighting means 5 are located in a recess 6. This positioning protects the image lens 42 and the two accompanying lighting lenses 52 from being scratched against the inside of the tubular structure 92. The inspection device 1 comprises a cover 62 that holds the image lens 42 and the accompanying lighting lenses 52 in place when needed, while allowing the image lens 42 and the accompanying lighting lenses 52 to be easily replaced radially with minimal disassembly of adjacent and / or internal parts. The cover 62 includes two chamfers 64, one on each side of the image sensor 4 and the two accompanying lighting means 5, ensuring there are no perpendicular edges associated with the recess 6 as these edges may hang up in profiles within tubular structures 92.

[0080] Referring to Fig. 3c, the inspection device 1 is formed with an opening 7 for a feedthrough wire, designed to provide at least one of power and communication between the upper connection 26 and the lower connection 29. The feedthrough wire allows transmission of power and communication originating from above the inspection device to be transmitted to tools under the inspection device and vice versa. The feedthrough may be controlled by a relay provided in a control unit in the inspection device, where the relay may be activated remotely (typically from topside) to allow power up or off of tools below the inspection device. This means that tools provided in the tool string below the inspection device may be powered and / or controlled via the inspection device by means of the mentioned relay. In one non-limiting embodiment, the relay may be K41 series commercially available from TE connectivity.

[0081] Fig. 4a shows a toolstring 100 connected to surface via the wireline 99. The toolstring 100 includes an upper purpose tool 120 connected to the upper portion 24 of the inspection device 1, and a lower purpose tool 140 connected to the lower portion 28 of the inspection device 1. This arrangement enables the inspection device 1 to inspect tasks performed by the upper purpose tool 120, the lower purpose tool 140, or a combination of tasks performed by both the upper purpose tool 120 and the lower purpose tool 140.

[0082] P31279 description and claims for PCT Fig. 4b shows an alternative embodiment of the toolstring 100'. In this configuration, the inspection device 1 is positioned at the distal end of the toolstring 100' and is connected in series with two upper purpose tools 120. In a tubular structure 92 that is obstructed, such as by a valve, the positioning of the inspection device 1 at the distal end enables it to inspect the lowermost part of the tubular structure 92.

[0083] Fig. 5 shows flow diagram representing a method 800 for inspecting the tubular structure 92. The method 800 comprises a step of providing 802 the toolstring 100, including the inspection device 1. The method 800 also comprises a step of moving 804 the toolstring 100 to a desired location. A step comprises inspecting 806 the inside of the tubular structure 92.

[0084] For an embodiment of the toolstring 100 that includes the upper purpose tool 120 and / or the lower purpose tool 140, the method may comprise performing an operation 808 within the tubular structure 92 using the upper purpose tool 120 and / or the lower purpose tool 140. The method 800 may comprise the step of inspecting 810 the interior of the tubular structure 92 before the operation is performed by the upper purpose tool 120 and / or the lower purpose tool 140. The method 800 may also include the step of inspecting 812 the interior of the tubular structure 92 while the operation is being performed by the upper purpose tool 120 and / or the lower purpose tool 140. Furthermore, the method 800 may comprise the step of inspecting 814 the interior of the tubular structure 92 after the operation has been performed by the upper purpose tool 120 and / or the lower purpose tool 140. The method may also comprise a step of removing 816 the toolstring 100 from the tubular structure 92.

[0085] It should be noted that the above-mentioned embodiments illustrate rather than limit the disclosure, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb "comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

[0086] P31279 description and claims for PCT The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0087] P31279 description and claims for PCT

Claims

C l a i m s1. An inspection device (1) for inspecting an inside of a tubular structure (92) downhole, the inspection device (1) comprises a main body (2), a plurality of image sensors (4), and at least one lighting means (5) accompanying each image sensor (4), the main body (2) having an outer surface (22) with an outer diameter, an upper portion (24) adapted to connect to surface equipment, and a lower portion (28), and forms a longitudinal axis (96),- wherein the lighting means (5) are arranged to emit light radially outwardly from the inspection device (1);- the image sensors (4) are arranged in a circumferential array in a plane (32) transverse to the longitudinal axis and facing radially outwardly from the inspection device (1); and- the inspection device (1) comprises at least one lens (42, 52) for each image sensor (4) and its accompanying lighting means (5) which is / are separate from the other image sensor(s) (4) and their accompanying lighting means (5), c h a r a c t e r i s e d i n that the main body (2) comprises one loadbearing portion (36) extending along the longitudinal axis between the upper portion (24) and lower portion (28) between each of the image sensors in the circumferential array (34).

2. The inspection device according to claim 1, wherein each of the load-bearing portions (36) has a diameter corresponding to the outer diameter of the outer surface (22) of the body (2).

3. The inspection device (1) according to any one of the preceding claims, wherein the lighting means (5) is spaced apart from the image sensor (4) along the longitudinal axis (96).

4. The inspection device (1) according to any one of the preceding claims, wherein each image sensor (4) is accompanied by at least two lighting means (5) spaced apart along the longitudinal axis (96) from the image sensor (4), at least one lighting means (5) is positioned on each side of the image sensor (4).P31279 description and claims for PCT5. The inspection device (1) according to any one of the preceding claims, wherein each image sensor (4), its accompanying lighting means (5), and the least one lens (42, 52) is positioned in a recess (6) in the main body (2).

6. The inspection device (1) according to any one of the preceding claims, wherein each image sensor (4) has an image lens (42), and each lighting means (5) has a lighting lens (52).

7. The inspection device (1) according to claim 6, wherein the image lens (42) is a plano-concave lens comprising a flat side (46) and a concave side (44), the concave side (44) of the image lens (42) facing the image sensor (4).

8. The inspection device (1) according to claim 6 or 7, wherein the lighting lens (52) is a plano-concave lens comprising a flat side (56) and a concave side (54), the concave side (56) of the lighting lens (52) facing away from the lighting means (5).

9. The inspection device (1) according to any one of the preceding claims, wherein inspection device (1) comprises an opening (7) for at least one feedthrough wire between the upper portion (24) and the lower portion (28).

10. The inspection device (1) according to any one of the preceding claims, wherein the lower portion (28) comprises a lower connection (29) adapted to connect to a lower purpose tool (140).

11. The inspection device according to claim 10, wherein the inspection device comprises a control unit, wherein the control unit comprises a relay for switching on and off power supply to the purpose tool (140).

12. The inspection device (1) according to any one of the preceding claims, wherein the lens (42, 52), or the image lens (42) and the lighting lens (52) is / are configured to function optimally in a liquid filled environment.

13. A toolstring (100, 100') for inspecting an inside of a tubular structure (92) downhole, c h a r a c t e r i s e d i n that:P31279 description and claims for PCT- the toolstring (100, 100') comprises an inspection device (1) according to any one of claims 1 to 13; and- the upper portion (24) is connected to a surface equipment.

14. The toolstring (100) according to claim 13, wherein the lower portion (28) is connected to a lower purpose tool (140).

15. The toolstring (100) according to claim 13 or 14, wherein the inspection device (1) is positioned in the toolstring (100, 100') such that it may inspect at least one of a pre-purpose-tool operation, during a purpose-tool operation, and a post- purpose-tool operation.

16. Method (800) for inspecting an inside of a tubular structure (92), c h a r a c t e r i s e d i n that it comprises the steps of:- providing (802) a toolstring (100, 100') according to any one of claims 14 to 16;- displacing (804) the toolstring (100, 100') to a desired position inside the tubular structure (92); and- inspecting (806) the inside of the tubular structure (92).

17. The method (800) according to claim 16, wherein the toolstring (100, 100') comprises a purpose tool (120, 140) and the method comprises the step of performing an operation within the tubular structure (92) using the purpose tool (120, 140).

18. The method (800) according to claim 17, wherein the method (800) comprises the step of inspecting (810) the tubular structure (92) before the operation is performed.

19. The method (800) according to claim 17 or 18, wherein the method (800) comprises the step of inspecting (812) the tubular structure (92) while the operation is performed.P31279 description and claims for PCT20. The method (800) according to any one of claims 17 to 19, wherein the method (800) comprises the step of inspecting (814) the tubular structure (92) after the operation is completed.P31279 description and claims for PCT

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